Respirator system for use with a hood or face mask

A respirator system for supplying breathable air to a hood or face mask comprising

• a housing containing a first chamber defining a component cavity,
• an air inlet plenum disposed in said housing,
• air filter means removably connectable to said housing for removing contaminants from ambient air passing therethrough, said air filter means communicating with ambient atmosphere external to said housing and with said air inlet plenum,
• blower means disposed in said component cavity and having an air inlet port and an air outlet port, said air inlet port communicating with said air inlet plenum,
• a motor disposed in said component cavity and operatively connected to said blower means,
• an air outlet plenum disposed in said component cavity and connected in fluid receiving relation to said blower air outlet port, said air outlet plenum being connectable in air supplying relation to said hood or mask for operation of the system in a powered air purifying respirator mode,
• valve means connected between said blower air outlet port and said air outlet plenum for permitting air, under pressure, to flow from said blower means into said air outlet plenum and for preventing air, under pressure, from escaping said air outlet plenum into said blower air outlet port,
• differential air pressure sensing means connected in fluid responsive relation between ambient atmosphere and said air outlet plenum for sensing when the difference between the pressure of air in said air outlet plenum and the pressure of ambient atmosphere is less than a preselected minimum value, and
• alarm means responsively connected to said sensing means for indicating when said pressure difference is less than said value.